Hi, I hatch eggs for my students. I have a HOvabator, styrafoam, with air. I've hatched a total of 3 times in the last 2 years. I've had terrible hatch rates. The first time, I followed the directions the incubator gave. The 2nd and 3rd times I've tried the dry -er hatch method. I live in the dry, dry S. CA desert, though. My hatch rates have been like 2/12, 4/12, 4/20. I know I could've had fertility issues on the first 2, since they weren't my own eggs. The last batch was shipped eggs. This time, I'm doing 12 shipped and gathering possibly some of my own and some local chicken farmer's. Please let me know what I can do to improve. I just bought a new hygrometer. Thanks for your help.